Field of the Invention and Related Art Statement
The present invention relates generally to chemical analysis, and more particularly to a cuvette auto-loading apparatus for successively supplying cuvettes into a reaction line of an automatic chemical analyzer.
There have been proposed various types of automatic chemical analyzers. In a calorimetric analyzer, a sample such as a serum and a reagent are delivered into a cuvette fed along a reaction line to form a test liquid and then the light absorption of the test liquid is photometered to effect a quantitative analysis. Such analyzers may be classified into a direct measuring system in which the test liquid contained in the cuvette is photometered and an indirect measuring system in which the test liquid transferred from the cuvette into a flow cell is photometered. From the view point of construction of the analyzer, the former system is superior to the latter system, because the construction can be made much simpler in the former system. As to the treatment of the cuvette, there are two systems. In the first system the cuvettes traveling along the reaction line are used repeatedly, while in the second system used cuvettes are removed from the reaction line and new cuvettes are fed successively into the reaction line. In the first system a mechanism must be provided for washing and drying the cuvettes, so that the whole apparatus is liable to be complicated in construction, large in size and expensive in cost. Further, the first system requires a great amount of a washing liquid and problems occur in treatment of waste washing liquid. If the washing is not effected sufficiently, contamination or carry-over may occur between successive test liquids, which affects the accuracy of measurement. Moreover, while the cuvettes are used repeatedly, they are liable to be damaged or scratched and therefore the measuring accuracy might be decreased. Contrary to this, in the second system the above problem can be entirely removed, because the cuvettes which have been once used are discarded. However, an automatic cuvette loader must be arranged for supplying new cuvettes into the reaction line. Known automatic cuvette loaders have several drawbacks in that they are of complicated construction and require very cumbersome treatment.
In order to solve the above-stated problem, there has been proposed an automatic cuvette loader having a simple construction for certainly supplying cuvettes in the reaction line successively in U.S. Pat. No. 4,634,575. In the automatic cuvette loading apparatus disclosed in U.S. Pat. No. 4,634,575, magazines containing a plurality of cuvettes are stocked in a magazine container of the apparatus and are supplied to the cuvette loading position one by one by means of a first slider which is moved in a first direction. Cuvettes contained in the magazine situated in the cuvette loading position are pushed out of the magazine one by one by sliding a second slider in a second direction perpendicular to the first direction toward the reaction line along a guide shaft to mount the cuvettes in recesses provided in a periphery of a cuvette holder constituting the reaction line of the automatic chemical analyzer. However, when the cuvettes are pushed out of the magazine one by one, it is necessary to align the cuvettes in row in the second direction in order to set the cuvettes in the recesses of the cuvette holder smoothly. In this known cuvette loader, while the side wall of a cuvette row formed by cuvettes situated in the cuvette loading position are urged against the inner wall of the magazine by means of the first slider, the cuvettes are pushed out of the magazine one by one by means of the second slider. Thus, there would occur a frictional force between the side walls of the cuvettes and the inner wall of the magazine, which affects the smooth loading of the cuvettes into the reaction line of the chemical analyzer. A further drawback exists that when the cuvettes are pushed against the inner wall of the magazine by the first slider they might be inclined or when the cuvettes are fed into the reaction line one by one by the second slider, the cuvettes might be caught somewhere in the magazine. Thus, the cuvettes could not be fed into the reaction line smoothly.